It's GOOD

The problem with American urban development patterns is that once a neighborhood has its amenities, new development grinds to a halt. Wealthier new residents have more political savvy than the old ones, and they use this to impose a protective NIMBY shield around the neighborhood.

Great point: "New housing comes with higher-end supermarkets, restaurants, and stores, which increase the value of the neighborhood faster than the new housing units can absorb." I personally find it sad that longtime residents have to be ok with the growth.

There are pretty more factors related with the success of gentrification process like the history of the area/space, interest of the community, social structure, an intense breakage of an era of culture and economic viability. There's no harm for the process if the aspects related with it are dealt in wisely and a wider list of its impact and effects over a period of at least a living of a generation is considered. What happens actually - planning is done for a period of 20-30 years and in this accelerated phase of development, its pretty difficult to predict the exact situation by virtue of the approach generally followed by the planners.